RICHLAND, Miss. — As Mississippi's senior senator stumps for votes in next week's GOP primary runoff, he's also trying to entice a new demographic — Democrats.

Sen. Thad Cochran's tea party-backed challenger, Chris McDaniel, and his supporters have criticized the senator's efforts to expand the electorate, calling it desperation. Democratic leaders also have criticized the move and urged members of their party to stay out of the GOP runoff.

But Cochran said Wednesday that he hopes, "the more the merrier will prevail in this election."

"I used to be a Democrat," Cochran said, referring to decades ago before his first election to the House of Representatives in 1972. "My parents were active in the Democratic Party. We made changes in our views about some of the policies of the parties, and over time they evolved into different parties. ... I'm a Republican member of the U.S. Senate, and it's a good thing for the state that I have been."

Only those who voted in Mississippi's June 3 Democratic primary are prohibited from voting in Tuesday's runoff, he said.

Rickey Cole, chairman of the Mississippi Democratic Party has claimed a super PAC that supports Cochran is offering "walking around money" for black Democratic votes.

Cochran denied buying votes but was unabashed about his decision to lure Democratic voters.

Since trailing McDaniel slightly in the June 3 vote, Cochran has been campaigning on his seniority and clout in Washington and his storied ability to secure federal financing, military projects and jobs for Mississippi.

McDaniel continues to run on ending such spending, shrinking government and growing anti-Washington and anti-incumbent sentiment.